The controversial copyright enforcement bill the Protect IP Act, or PIPA, may be amended on the Senate floor later this month in response to ongoing concerns about its provisions affecting ISPs and the domain-name system, the bill's chief sponsor said. Senator Patrick Leahy, a Vermont Democrat and chief sponsor of the Protect IP Act said Thursday he plans to offer an amendment that would require a study of the impact of the ISP provisions in the bill before they are implemented.